Differential Serodiagnostics of Latent Stages of Syphilis Based on Measuring IgG and IgM Levels towards Extended Panel of Recombinant Antigens of T. pallidum.

Immunochips containing 12 recombinant antigens of T. pallidum (Тр15, Тр17, Тр47, TmpA, Тр0163, Тр0277, Тр0319, Тр0453, Тр0684, Тр0965, Тр0971, and Тр1038) were prepared to assay for IgG and IgM in serum samples (n=68) of healthy individuals and patients with the latent stages of syphilis. The linear discriminant analysis of detected IgG and IgM differentiated three groups of serum samples as 1) early latent syphilis; 2) seroresistant early latent syphilis; and 3) late latent syphilis with overall differentiation potency of 95.6% (88.9-100%). The samples of all syphilis patients were differentiated from the samples of healthy individuals with 100% specificity.

[Diagnostic imminoarray assay for characterization of immunoglobulin igg and igm level in syphilis patients serum towards 12 recombinant antigens of t. pallidum before and after the therapy.]

The aim of the study was to characterize the dynamics of immunoglobulin IgG and IgM level in syphilis patients serum at different stages of the disease before and after the therapy towards 12 diagnostic antigens of T. pallidum in an microarray assay and to evaluate these data as possible prognostic markers. The dynamics of immunoglobulin IgG and IgM level was measured in the reaction of indirect immunofluorescence using microarray and compared to the results of non-treponemal RPR test and treponemal tests as EIA and reaction of passive hemagglutination. In microarray assay diagnostically high level of IgM in patients with primary, secondary and early latent and late latent syphilis decreased dramatically to zero after the successful therapy. Continuously high level of IgM after the therapy proposes the persistence of infection agents in the organism and points out the need of additional antimicrobial treatment. In most of the cases anti-treponemal IgG level also declined after the successful therapy and this confirms the appropriate treatment. The results of microarray assay coincide with the results of other mentioned laboratory tests for syphilis diagnostics. Microarray assay with the recombinant T. pallidum antigens gives the perspective for creating methods with wider spectrum of diagnostic and therapy control options using the IgM immunoglobulin level as a marker for successful syphilis treatment.

Immunochip for Syphilis Serodiagnostics with the Use of Extended Array of Treponema pallidum Recombinant Antigens.

An immunochip for multiple parallel detection of specific serum IgG in serological screening for syphilis is based on the use of an extended array of Treponema pallidum recombinant proteins and includes traditionally used immunodominant antigens (Tp15, Tp17, Tp47, and TmpA) and new synthetic proteins (Tp0277, Tp0319, Tp0453, Tp0684, Tp0965, and Tp1038). The use of individual antigens has demonstrated high analytical value of Tp0277 (periplasmatic C-terminal protease), Tp0319 (cytoplasmic membrane-associated lipoprotein TmpC), and external membrane-associated protein Tp0453 with transporting function, all of them improving significantly the efficiency of screening for syphilis in comparison with the traditional array of antigens. Multiparametric analysis of the results obtained on the immunochip with the use of linear discriminant analysis confirmed the efficiency of extended array of T. pallidum diagnostic antigens. Due to proposed modification, the "positive" and "negative" sera are clearly differentiated: the serological study showed 94.1% sensitivity and 100% specificity.